// Monitor enumeration for the settings UI.
//
// The screen-capture backend itself selects a monitor by index; this file
// provides a way to list the available monitors so the GUI can present a
// friendly picker instead of a raw index.
//
// Hyprland exposes monitor info via the `hyprctl monitors` command. Other
// Wayland compositors would need a portal-based enumeration; for now we only
// implement the Hyprland path (the primary dev environment) and return a
// clear error elsewhere.

package capture

import (
	"encoding/json"
	"errors"
	"os/exec"
)

// Monitor describes one capturable output.
type Monitor struct {
	Index   int    // capture StreamIndex to pass to OpenPipeWire
	Name    string // compositor name, e.g. "eDP-1"
	Width   int
	Height  int
	Primary bool
}

// ErrNoMonitors is returned when monitor enumeration is unsupported or fails.
var ErrNoMonitors = errors.New("capture: monitor enumeration unavailable on this compositor")

// ListMonitors returns the available monitors for the GUI picker.
func ListMonitors() ([]Monitor, error) {
	if hyprctlAvailable() {
		return hyprctlMonitors()
	}
	return nil, ErrNoMonitors
}

// hyprctlAvailable reports whether the Hyprland monitor command exists.
func hyprctlAvailable() bool {
	_, err := exec.LookPath("hyprctl")
	return err == nil
}

// hyprctlMonitor is the JSON shape emitted by `hyprctl monitors -j`.
type hyprctlMonitor struct {
	ID          int    `json:"id"`
	Name        string `json:"name"`
	Width       int    `json:"width"`
	Height      int    `json:"height"`
	Description string `json:"description"`
	Focused     bool   `json:"focused"`
}

// hyprctlMonitors lists monitors via the Hyprland IPC command.
func hyprctlMonitors() ([]Monitor, error) {
	out, err := exec.Command("hyprctl", "monitors", "-j").Output()
	if err != nil {
		return nil, ErrNoMonitors
	}

	var raw []hyprctlMonitor
	if err := json.Unmarshal(out, &raw); err != nil {
		return nil, ErrNoMonitors
	}

	monitors := make([]Monitor, 0, len(raw))
	for _, m := range raw {
		monitors = append(monitors, Monitor{
			Index:   m.ID,
			Name:    m.Name,
			Width:   m.Width,
			Height:  m.Height,
			Primary: m.Focused,
		})
	}
	return monitors, nil
}